The invention relates to a gearshift for a bicycle with an electric auxiliary drive, comprising a stepped gear system formed as a gear hub system or derailleur gear system and an electromechanical actuator for triggering a gear change of the gear system.
Bicycles are usually equipped with a gearshift whose gear system can be constructed as a gear hub system or as a derailleur gear system. The rider selects the appropriate gear by a hand switch that can be constructed, e.g., as a rotary switch mounted on the handle bar. This switch is connected to the gear system by a Bowden cable. In addition to rotary switches, toggle or rocker switches mounted on the handle bar or on a frame part are also common.
An electromechanical gearshift for a bicycle is known from DE 41 28 866 A1. This gearshift comprises a control switch, a gear system, for example, a gear hub or a derailleur gear system, and an electromechanical adjustment device. The adjustment device is coupled with a Bowden cable, so that the gear system can be switched off by a shifting of the adjustment device.
Conventional gearshifts for a bicycle can be shifted at any time, in particular, also under loading, that is, when the torque transmitted from the rider to the pedals is at a maximum. Both for gear hub systems and also derailleur gear systems, however, increased wear occurs when they are shifted under high loading.
Bicycles with electric auxiliary drives are also affected by this problem. Typically, the rider reduces the driving power before a manual shifting operation, then manually performs the shifting operation, and then he can reset, that is, increase the driving power again, wherein this control procedure is also carried out manually. A proper and material-preserving operation of a conventional gearshift for a bicycle with an electric auxiliary drive is therefore not especially convenient or easy to operate.